Nonlinear sound absorption of coiling-up space under high amplitude acoustic excitation

In this paper, we investigate the nonlinear sound absorption of coiling-up space under high amplitude acoustic excitation with analytical method based on JCAL model, numerical simulation method based on finite element, and experimental methods based on impedance tube. The analytical model is established by analogy with porous material. The high incident sound pressure level (ISPL) causes acoustic vortices to arise at the inner corners of the coiling-up space, converting part of the acoustic energy into the kinetic energy of vortices, which is ultimately dissipated by thermoviscous loss. The nonlinear acoustic effects increase the real part of normalized acoustic impedance, which is more dramatic as the ISPL increases. The results of the parametric analysis demonstrate that the effect of ISPL on the absorption coefficient at peak frequency decreases as the total equivalent length increases.